import { useEffect, useRef } from 'react';
import { useEditorStore } from './store';
import type { Annotation } from '../../lib/annotations/types';

export function useAutosave() {
  const { documentId, annotations, setSaveStatus, setAnnotations } = useEditorStore();
  const timeoutRef = useRef<number | null>(null);
  const isFirstLoad = useRef(true);

  // Initial load
  useEffect(() => {
    if (!documentId) return;

    let active = true;

    async function load() {
      try {
        const res = await fetch(`/api/v1/documents/${documentId}/annotations`);
        if (!res.ok) throw new Error('Failed to load annotations');
        const data = await res.json();
        
        if (active) {
          setAnnotations(data.data as Annotation[]);
          setSaveStatus('saved');
          isFirstLoad.current = false;
        }
      } catch (err) {
        console.error('Error loading annotations:', err);
        if (active) setSaveStatus('error');
      }
    }

    load();

    return () => { active = false; };
  }, [documentId, setAnnotations, setSaveStatus]);

  // Debounced save
  useEffect(() => {
    // Don't save on the initial load!
    if (isFirstLoad.current) return;
    if (!documentId) return;

    setSaveStatus('saving');

    if (timeoutRef.current) {
      window.clearTimeout(timeoutRef.current);
    }

    timeoutRef.current = window.setTimeout(async () => {
      try {
        const res = await fetch(`/api/v1/documents/${documentId}/annotations`, {
          method: 'PUT',
          headers: {
            'Content-Type': 'application/json',
            'X-Requested-With': 'XMLHttpRequest'
          },
          body: JSON.stringify({
            data: annotations
          })
        });

        if (!res.ok) throw new Error('Failed to save');
        setSaveStatus('saved');
      } catch (err) {
        console.error('Error saving annotations:', err);
        setSaveStatus('error');
      }
    }, 500); // 500ms debounce

    return () => {
      if (timeoutRef.current) window.clearTimeout(timeoutRef.current);
    };
  }, [annotations, documentId, setSaveStatus]);
}